This complete guide to vitamin D provides you all information you need to know about vitamin D - What are the benefits of vitamin D - How does vitamin D work, how is it absorbed in your body - How does vitamin D increase your health - What is the effect of vitamin D on quality of life, blood, skin, breastfeeding, depression, menstrual cycle - What is the effect of vitamin D on several sicknesses - What is the effect of vitamin D on weight control - Necessity of vitamin D for special groups: babies, infants, children, pregnant women, veges, pets - What are the minimum and maximum levels required or advised - Best sources of vitamin D (food, sun, supplements) - How to test your own level, do you have deficiency or overdose - How to increase or decrease vitamin D levels - Vitamin D deficiency and overdose, effect, risks, signs, cause, treatment - Best supplement brands